1. Technical Field
The present invention relates to memory devices and, more particularly, to writing magnetic domains to racetrack memory using heating or cooling to generate magnons.
2. Description of the Related Art
Racetrack memory offers high storage densities and high read/write performance by encoding data in walls between magnetic domains along a nanowire. Stored domains are pushed through the memory using a spin-coherent electric current, which moves all domain walls in a consistent direction, regardless of the direction of its particular magnetization.
The injection of domain walls into a magnetic nanowire at specific locations conventionally is accomplished using magnetic fields applied by adjacent current-carrying wires. Such wires are usually disposed perpendicular to the magnetic nanowire. This method of injection uses large currents to generate the necessary magnetic field, which necessitates the use of large amounts of power and large on-chip transistors.
Another injection method uses spin-torque transfer from a spin-polarized current passing from a second ferromagnetic conductor into the magnetic nanowire through a non-magnetic, insulating tunnel barrier. This method injects domains by flipping the magnetization of the nanowire locally. This method also uses relatively large currents and is furthermore susceptible to breakdown of the insulating tunnel barrier between the magnetic nanowire and the ferromagnetic conductor.